In a wireless communication system a data stream will most likely experience multiple reflections (multipath) while propagating between the transmitter and the receiver. Multipath fading implies that multiple copies of the transmitted signal follow different paths and reach the receiving antenna with different time delays. In such cases, the received signal strength at a given time is the result of destructive and constructive interference of the multiple paths arriving from different directions. Destructive interference may degrade the performance of the detector and, therefore, it may adversely affects the system capacity. However, by using multiple antennas at the receiver and with appropriate digital signal processing methods, a multipath may be exploited to enhance the performance and robustness of the receiver and to increase the reliability of the communications link. The receiving antennas may need to be spaced sufficiently far apart so that the signal each antenna sees may not be correlated with the signals seen by the other antennas. Selection diversity may be utilized in mitigating multipath fading.
The algorithm for selection diversity is based on selecting the best signal among all the signals detected at the receiver antennas. If Pi denotes the power estimated at antenna i at the receiver, the selection diversity scheme may select antenna jas the receive antenna if Pj>Pi, i≠j. Higher accuracy in estimating the powers Pi may result in higher probability of the right receive antenna being selected, and in better performance of the selection diversity scheme. Factors that affect the accuracy of the power estimates Pi may include the presence of impairments, such as noise, transients and offsets, for example.
Impairments, such as noise, transients and offsets, corrupt the power estimates Pi and may result in misestimations of the power during an antenna selection process. Such misestimations of power may lead to the selection of antenna j, for example, as the receive antenna, even if Pj<Pi for some other antenna i.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.